Region bounds, error margins and certified positivity in the numerical conformal bootstrap; Or the first mathematically rigorous bounds on the 3d Ising CFT critical exponents
Abstract
Numerical conformal bootstrap bounds are commonly called rigorous, yet as published they are not theorems: they hold at sampled points rather than on regions of parameter space, for truncated rational approximations of the conformal blocks, for a finite list of spins, and up to floating-point rounding. We close all four gaps. We show how to search efficiently for functionals positive on regions, including external-dimension space; how positivity on the large-spin crossing vectors can be imposed as such a region constraint; how new analytic bounds on the conformal-block recursion relations give functionals positive on the true, untruncated crossing vectors; and how to certify the positivity of these functionals in exact arithmetic. The certification rests on Bernstein-basis positivity certificates in up to three variables, exact arithmetic in ℚ(√2), a compactified treatment of the infinite spin tail, and an explicit bound on the difference between the true blocks and their truncations, so that infinitely many positivity conditions reduce to finitely many machine-checked sign conditions. As a flagship application we certify an exclusion region in the (Δσ,Δε) plane: for Δσ∈[0.505,0.5405] all of Δε∈(1/2,3] is excluded except a small rectangle containing the 3d Ising island, giving rigorous two-sided bounds on the critical exponents η and ν under explicitly stated spectrum assumptions. The analytic inputs for the mixed σ-ε system, which would remove the spin-2 gap assumption, are also proved. The same methods prevent common practical failure modes and can make bootstrap searches faster: region bounds turn the mapping of an island into a handful of one-dimensional bisections. The essential code to reproduce the search and the certification, and all machine-checkable certificates, are released.
Related
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BibTeX
@misc{reehorst2026region,
title = {{Region bounds, error margins and certified positivity in the numerical conformal bootstrap; Or the first mathematically rigorous bounds on the 3d Ising CFT critical exponents}},
author = {Marten Reehorst},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.20701},
eprint = {2610.20701},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.20701},
}
RIS
TY - UNPB
TI - Region bounds, error margins and certified positivity in the numerical conformal bootstrap; Or the first mathematically rigorous bounds on the 3d Ising CFT critical exponents
AU - Marten Reehorst
PY - 2026
DA - 2026/10/14
PB - arXiv
DO - 10.48550/arxiv.2610.20701
UR - https://arxiv.org/abs/2610.20701
AB - Numerical conformal bootstrap bounds are commonly called rigorous, yet as published they are not theorems: they hold at sampled points rather than on regions of parameter space, for truncated rational approximations of the conformal blocks, for a finite list of spins, and up to floating-point rounding. We close all four gaps. We show how to search efficiently for functionals positive on regions, including external-dimension space; how positivity on the large-spin crossing vectors can be imposed as such a region constraint; how new analytic bounds on the conformal-block recursion relations give functionals positive on the true, untruncated crossing vectors; and how to certify the positivity of these functionals in exact arithmetic. The certification rests on Bernstein-basis positivity certificates in up to three variables, exact arithmetic in ℚ(√2), a compactified treatment of the infinite spin tail, and an explicit bound on the difference between the true blocks and their truncations, so that infinitely many positivity conditions reduce to finitely many machine-checked sign conditions. As a flagship application we certify an exclusion region in the (Δ_σ,Δ_ε) plane: for Δ_σ∈[0.505,0.5405] all of Δ_ε∈(1/2,3] is excluded except a small rectangle containing the 3d Ising island, giving rigorous two-sided bounds on the critical exponents η and ν under explicitly stated spectrum assumptions. The analytic inputs for the mixed σ-ε system, which would remove the spin-2 gap assumption, are also proved. The same methods prevent common practical failure modes and can make bootstrap searches faster: region bounds turn the mapping of an island into a handful of one-dimensional bisections. The essential code to reproduce the search and the certification, and all machine-checkable certificates, are released.
ER -